Timing, or beats, in humor is all about how the joke should play out. One must not issue it to quickly, nor in the wrong order, nor explain too far. If one rushes the joke, the humor is past before the people have time to fully appreciate it. If in the wrong order, it becomes muddled, and leave the audience confused. If explained too far, the audience fails to achieve their own humor.
Rushing it tends to be portrayed as cramming several jokes in at once. They can be orchestrated together, with skill, but are often just placed without reverence to escalating the component jokes into a crescendo of humor. Instead it will tend to fall flat. In the wrong order, it creates a discordance and it plays out poorly, leading to a disharmonious conclusion. Over explaining the joke instead interrupts the flow of the humor and leads to cacophonous resonance which echoes several beats beyond it's intrusion.
You may wonder why I've used musical terms to explain humor. The truth is they have a surprising number of similarities. Both have to be well composed. Both sound off when beats are missing or fall out of order. A single chord can throw off an entire symphonic recital, much as a single bad joke can ruin a well constructed piece of comedy.
The final problem to watch for is beating the joke to death. It's not that a joke may not be repeated or become the running joke; but it does require that they not be repeated so often as to lose their humor. Again, this is a matter of timing. Much like music or song, a chorus can be repeated, but if you repeat it too often, it strains the ear.
I'll use a personal example:
I was working on a romantic comedy, and was trying to show the protagonist in a non-harmonious relation with someone. It went well, but later in review, I found that I had stated, as part of the joke, that she was a bitch. The audience should deduce that she was being a bitch. That single line wasn't needed and it's inclusion blew the rhythm of the joke by going a beat too far.
It would or at least should get cut in editing, but never assume that the editor has a good sense of comedic timing. By removing this impediment, the scene flowed more seamlessly into the next. It also allows the audience to make their own moral judgements, which is dangerous, but a crafted risk. If you don't allow the audience to do this, you risk alienating them altogether.